
import {useEffect ,useRef } from "react";

export default function App() {
  const inputRef = useRef(null);
  useEffect(()=>{
     console.log(inputRef); 
     console.log(inputRef.current); 


  },[])
  return <div>
     用户名:<input type="text" className="uesrname" ref={inputRef}/>

  </div>;
}
